This invention relates to a method and apparatus for setting the shut height of dies in a press and, more particularly, to a gauge for setting the shut height of dies and the method for using the same.
Mechanical presses are used throughout industry in a variety of forming applications such as forming, piercing, drawing, blanking, bending, stamping and the like. Presses vary in size from just several ton capacity to up to hundreds of ton capacity and are typically large and expensive pieces of equipment. Parts are formed in the press by placing the workpiece between opposed dies mounted in the press and bringing the dies together by means of a reciprocable drive mechanism. The forming dies are formed from hardened tool steel and are accurately machined for precision forming of parts. They are of varying size and are also expensive items of equipment. Mechanical presses are made more versatile by providing the presses with adjustable slides on which one of dies is mounted for varying the distance between the slide and the press bed so that the press can accommodate dies of different shut heights.
Vertical misalignment of dies is a major cause of premature die wear and damage and overloading of presses. Accurate setup of the dies in the press is therefore of utmost importance. Moreover, it is occasionally necessary to realign the dies during operation to compensate for vertical backup of the press. For purposes of die setup, dies are provided with set blocks which are blocks of metal accurately machined such that when the press ram is at its bottom position and the dies are in their fully closed position with the workpiece therebetween there exists a small, predetermined distance between the end of the set block and the opposed die which defines the desired separation between the dies in their closed position. This distance is typically on the order of 0.010 inch.
Heretofore, dies have been setup by a number of methods. First, they have been setup by a visual approximation in which the setup man attempts to determine by sight the small gap between the end of the set block and the opposed die. Second, dies have been setup by the use of a thin piece of cardboard or paper not uncommonly of unknown thickness, being inserted between the end of the set block and the die with the die being brought together until the paper can just be pulled out. Third, dies have been setup by placing a small diameter deformable material on the end of the set block, for example, a piece of solder wire, lowering the die to flatten the wire, and periodically measuring the thickness of the flattened wire with a pair of calipers to arrive at an approximation of the required 0.010 inch clearance. Each of these methods falls far short of providing accurate setup of the dies. A fourth method, which may be referred to as a trial and error method, involves placing sample workpieces in the dies and operating the press with successively smaller clearances observing the degree of deformation of the workpieces while sensing the intensity of the sound and vibration of the press occurring during deformation to arrive at some approximation of the correct shut height. This method also is highly inaccurate but further results in damage to the dies and the press during the setup operation itself.
If the dies are set with too wide a gap, the parts are not correctly formed resulting in substantial waste of material. Since the dies themselves and the presses have some capacity to absorb shocks through distortion and deflection, it is common in practice for the die setup man to err toward placing too narrow a gap rather than too wide a gap between the set block and the die. It is not uncommon for the dies to be setup with no gap at all allowing the die and press to distort and deflect during operation. As a result, during press operation the set block is actually driven into the opposed die. This means that the set block must be made large to absorb the shocks. But moreover, this method results in greatly excessive wear of the dies and press parts, poor part quality, distortion, excessive noise, and hazards to press operators from breakage of the dies during press operation.
It is an object of this invention to provide a gauge and method of using same which allows for precise setup of dies in a press to achieve maximum part quality and maximum die and press life.
It is another object of this invention to eliminate inaccuracies, approximations, and trial and error in die setup and to establish accurate and consistent setting of the shut height of dies in presses.
It is another object of this invention to provide a gauge for the setting of the shut height of dies accurately to within 1/1,000 of an inch.
It is another object of this invention to provide a gauge for setting the shut height of dies which is simple in construction, easy to operate and permits fast setup of dies, light, compact, and versatile such that it may be moved from one press to another and may be used with all type of presses and all types of set blocks.
It is another object of this invention to provide a gauge which can detect vertical misalignment of dies which results in excessive die and press wear and damage thereby reducing costs and loss of production time resulting from the need for repair, reconditioning or replacement of dies and press parts.
It is another object of this invention to achieve precise setup of dies thereby reducing the hazards to press operators resulting from imprecise setup of the dies.
It is another object of this invention to provide a gauge that will detect if interferences exist in the dies.